Peroxycarboxylic acid compositions can be effective antimicrobial agents. Methods of using peroxycarboxylic acids to clean, disinfect, and/or sanitize hard surfaces, textiles, meat products, living plant tissues, and medical devices against undesirable microbial growth have been described (U.S. Pat. No. 6,545,047; U.S. Pat. No. 6,183,807; U.S. Pat. No. 6,518,307; U.S. Patent Application Publication No. 2003-0026846; and U.S. Pat. No. 5,683,724). Peroxycarboxylic acids have also been used in various bleaching applications including, but not limited to, wood pulp bleaching/delignification and laundry care applications (European Patent 1040222B1; U.S. Pat. No. 5,552,018; U.S. Pat. No. 3,974,082; U.S. Pat. No. 5,296,161; and U.S. Pat. No. 5,364,554). The desired efficacious concentration of peroxycarboxylic acid may vary according to the product application (for example, ca. 500 ppm to 1000 ppm for medical instrument disinfection, ca. 30 ppm to 80 ppm for laundry bleaching or disinfection applications) in 1 min to 5 min reaction time at neutral pH.
Enzymes structurally classified as members of family 7 of the carbohydrate esterases (CE-7) have been employed as perhydrolases to catalyze the reaction of hydrogen peroxide (or alternative peroxide reagent) with alkyl esters of carboxylic acids in water at a basic to acidic pH range (from ca. pH 10 to ca. pH 5) to produce an efficacious concentration of a peroxycarboxylic acid for such applications as disinfection (such as medical instruments, hard surfaces, textiles), bleaching (such as wood pulp or paper pulp processing/delignification, textile bleaching and laundry care applications), and other laundry care applications such as destaining, deodorizing, and sanitization, and personal care applications (U.S. Pat. Nos. 7,964,378; 7,951,566; and 7,723,083; Published U.S. Patent Application No. 2008-0176299 to DiCosimo et al.; and Published U.S. Patent Application Nos. 2012-0317733 and 2012-0328534 to Chisholm et al.). The CE-7 enzymes have been found to have high specific activity for perhydrolysis of esters, particularly acetyl esters of alcohols, diols and glycerols. Variant CE-7 perhydrolases derived from several species having improved performance been reported by DiCosimo et al. (U.S. Pat. Nos. 7,927,854; 7,923,233; 7,932,072; 7,910,347; 7,960,528; 8,062,875; 8,206,964; 8,389,254; and 8,389,255; and Published U.S. Patent Application Nos. 2011-0236336 and 2011-0236338).
Previously reported CE-7 carbohydrate esterases having perhydrolytic activity (both wild type and variants thereof) comprised a conserved structural “signature” motif as defined by Vincent et al. (J. Mol. Biol., 330:593-606 (2003)). More specifically, the CE-7 signature motif used to structurally identify and define members of the CE-7 carbohydrate esterase family comprises three conserved submotifs: 1) an “RGQ” submotif of Arg118-Gly119-Gln120, 2) a “GXSQG” submotif of Gly186-Xaa187-Ser188-Gln189-Gly190, and 3) an “HE” submotif of His303-Glu304 (residue numbering and orientation relative to the Thermotoga maritima reference sequence provided as SEQ ID NO: 2).
While the vast majority of enzymes classified as CE-7 carbohydrate esterases are comprised of the signature motif defined by Vincent et al., several polypeptide sequences have been added to family 7 of the carbohydrate esterases that do not contain the “HE” submotif (Cantarel et al., “The Carbohydrate-Active EnZymes database (CAZy): an expert resource for Glycogenomics”, NAR, 37:D233-D238 (2009)). The presence of perhydrolytic activity within this subgroup has not been reported.
Incorporation of perhydrolytic enzyme technology into some applications may require the identification of new perhydrolytic enzymes. As such, there remains a need to identify additional enzyme catalysts comprising polypeptide having significant perhydrolytic activity.